Improvement in methods of producing printing-surfaces



PATENT OFFICE,

JOHN HENRY BANKS, OF'BATTERSEA, ASSIGNOR TO GEORGE MONEY BRIGHT AND "FRANCIS BARROW, OF LONDON, ENGLAND.

Specification forming part ofLetters Patent N o. 175,009, dated March 21, 1876'; application filed December 526, 1874.

To all who'm'it may concern:

Be it known-that I, J OHN' HENRY BANKs,

of 11' Lavender'Road,Batter-sea, in the county of Surrey, England, gentleman, a subject'of the Queen of Great Britain, have invented or vention, and in what manner the same is to be performed, to be'particularly described and ascertained in and by the following statement thereof -that is to'say: v

The object of my invention is mainly to produce from a drawingvnpon'ipaper, or a letter press, copper-plate, or lithographic print or drawing, a raised surface block applicable for type-printin g, or a plate. similar to an epgraved coppervor steel plate,'applicable for printing by the ordinary copper-plate or lithographic press.

The raised surface-plates can be produced either flat, or they'may be cylindrical, for the purpose of printing upon calico, and such like purposes, metal dies to be used as seals, or for stamping paper and such like uses, or to be used as embossing-plates forbook-binders for stamping or embossingbook-coversor leather-or other substances-in high relief,or for other purposes connected with the printing, bookbinding, die-sinking, or embossing trades, Where printing or embossing is used.

To'produce the above results either from a drawing, letter-press print, photograph, or

any work of art on'paper, or painting, I first obtain a photographic negative in the ordinary way'by means of a rectilinear lens and ordinaryc'amera, upon glass, No. 1, except that I lastly develop it with a solution of bichloride of mercury, wash this'ofl' with cold water, and then put iodide of potassium; Wash thisofl' with cold water, and then put hydrosu'lphuret of ammonia-say, one drain totwo ounces of Water-for the purpose of making all the white parts in the print or drawing as opaque andblack as possible on the glass, so thatthe sun" or artificial light used in printing the design upon the prepared glass N0. 2 (which I hereafter describe) shall not act upon the White parts, but only on the drawing.

1 afterward prepare a glass, No. 2, by laying it perfectly flat, and, accordingvto the quality of the lines or work on thedesign, so I make the thickness or thinness of the film of gelatine or chondrine, which I prepare as follows: I take two ounces of gelatine,chondrine, best Russian or French glue, madefrom the pates of the buffalo or from parchment cuttings, and cut it into small shreds, and then pour upon it one pint and a half of cold water and let it stand until it is dissolved, say about ten hours, and then gently make it hot, not to boil nor burn, and, after laying the glass flat, I pour on the glass, if twelve inches by ten inches, three ounces, and then leave it to dry. After it is dry I then make up in a bath a solution composed of one ounce of bichromate of potash or other bichromate, or peroxide of chromium, to one quart of cold Water, with about half a dram of hydrate of lime. I then place the glass containing the dried gelatine film upon it into the bath, taking care that the mixture covers it entirely, and when it has remained in three or four minutes I take the glass out and put it on its end to drain and dry, taking care that no daylight enters the roomonly gas or dark yellow light. When this prepared glass N o. 2 is perfectly dry and the film hard, I take an ordinary pressureframe with a plate'glass front, and on the plateglass I lay the photographic negative glass N 0. 1, with the silvered side upward, and upon this side I place the film side of the glass No. 2 ppon it, and then I place a piece of black velvet upon the back of glass No. 2, press the whole tightly together, and expose the glass to the suns rays, or to a magnesium, electromagnetic, or other white light, for about five, ten, or twenty minutes, and then I obtain a printed impression that is, the design upon the gelatine. The negative glass being transparent and the white parts being black, the sun or other light can only go through the transparent parts, and so converts the printed portion of the gelatine into an almost insoluble compound, leaving the white portions perfectly soluble. I then take it into the darkened room and immerse it in cold water-one quart mixed with ten grains of iodine or sixteen grains of iodide of potassium-from a quarter to half an hour. I then take it out and put it into a bath of cold \vater--two quarts mixed with twenty drops of am moniafor about a quarter of an hour; then take it out and place it in a bath of two quarts of cold water mixed with one ounce of acetic acid for about five or ten minutes, to develop the edges of the design that have not been raised up. By this means lobtain a gelatine surface mounted on glass and having the white portions of the drawing raised up to a very great height-quite as high as any wood engraving is cut in depthand the drawing is level and sunk. The gelatine surface has also been strengthened and toughened, so that a cast can afterward be readily taken from it, whereas heretofore the casts taken from gelatine plates have been very imperfect.

I then mix some plaster-of-paris or cement and take a cast, which gives the design raised up and the white portions indented similar to wood engraving. Should any of the white portions not be sufficieutly deep, I then proceed to deepen them. One method I have is to roll over the raised portions of the plaster cast a mixture of printing-ink and copal, or some one of the varnishes now in use commercially, and when dry I dip the plaster mold into a bath of very weak soap one part and cold water five hundred parts, and brush away with a soft brush the unprotected plaster and afterward I harden the plaster with weak alum and pyrogallic acid and water until the air-bubbles cease to rise from it.

Another way I have is to .cut away with a gouge all the whites that are not sufficiently deep enough; but if I require to take a casting in plaster-of-paris for stereotyping purposes, I do not use the soap water, but harden the first cast by immersing it in a bath of hot size, a little treacle, and peroxide of chromium until the air-bubbles cease to rise from it, and then expose it to light, and while wet I lay a frame upon it, pour in the plaster-ofparis, and just before it sets, I put it under pressure, and the loose water being pressed out gives a much sharper casting.

If an electrotype is required instead of a stereotype casting, I then take the plaster cast that has been taken from the gelatine film and soak it in cold water until bubbles cease to rise from it; or, by preference, I lay the plaster cast in a bath of cold water, face upward, with the water reaching nearly to the face, and keep the block in the water until the water has permeated through the block to the face. I then make the face of the plaster hot by placing it over a gas flame, and put a frame on the face, and pour on it a preparation of hot wax mixed withresin and lard, which mode I prefer, and thus take an impression in wax from the plaster mold. I afterward polish this wax impression in the usual way with black lead, or coat it with metal by using mercury. By washingthe mold with spirits of wine, and when nearly dry allowing the fumes of mercury to settle on the face, I get a metallic covering, which readlly receives a surface of copper without bein g brushed, whereby the fine lines are kept 1ntact.

In a similar manner the surface of the gelatine plates themselves may be coated with a thin film of mercury to enable an electrotype to be taken direct from them.

To produce a copper plate si milar to a copperplate engraving, I take a negative with the lights and shades reversed, and by adapting the same portion of the process of glass 1 and 2, which relates to the printed representat on on glass No. 2, and raising the surface with acetic acid and water only, 1 then take a plas ter mold, and from it a casting in wax to electrotype, and so produce a copper plate, as thick as an ordinary engraved copperplate, with the drawing indented exactly similar to an engraved plate, which can be printed by the ordinary copper-plate press.

For some work I modify the mode by not taking a negative, but by placing the print in contact on glass No. 2, it acts as the negative, and after it is reproduced on glass N0- 2, and proceeding as already described, a plate is produced which can be printed from in the ordinary manner.

Having now described the nature of my invention, and the manner of performing the same, what I claim is- 1. The herein-specified improvement in the art of preparing gelatine surfaces upon glass for receiving the imprints of photographic negatives, from which imprints printing-surfaces are to be obtained, which improvement consists in pouring warm gelatine on the glass, and after it becomes dry soaking 1t 1n a solution of bichromate of potash, or other bichromate or peroxide of chromium, hydrate of lime, and cold water, and then drying without exposure to daylight, as and for the purposes set forth.

2. The herein-specified improvement in the art of treating gelatine surfaces upon glass after an imprint from a photographic negative has been made upon them, in order that a printing-surface may be obtained, which 1 mprovement consists in taking the glass, with its imprinted gelatine surface, into a darkened room, and bathing it, successively, in a solution of iodine or iodide of potassium, a solution of ammonia, and a solution of acetic acid, as and for the purposes set forth.

3. The herein-specified improvement in the art of producing printing-surfaces, which consists in preparing the plaster cast by soakinglt in water, or laying it in a bath, face upward,1n cold water nearly to reach the face, and when the water has permeated to the face, removing the cast from the bath, and thoroughly drying its face by the application of heat prior 6. The herein-specified improvement in the art of producing printing-surfaces, which consists in preperin g plaster casts, gelatine plates, or wax impressions for electrotyping, by causing vapor or fumes of mercury to settle on and form a thin film upon the surface, substantially as and for the purposes set; forth.

JOHN HENRY BANKS.

Witnesses:

THOMAS LAKE, CHARLES HAYNES,

No. 17 Gracechurch Street, London. 

